1. Field of the Invention
The present invention relates to a thermal transfer dye image-receiving sheet usable for a thermal imaging printer by which sublimating dye images can be thermally transferred on the image-receiving sheet. More particularly, the present invention relates to a thermal transfer dye image receiving sheet that can be smoothly delivered through a printer without fuse-adhering to an ink ribbon even when the image-receiving sheet is fed into the printer incorrectly, and that is strongly resistant to an undesirable transfer of dye images from a dye image-receiving layer of a dye image-receiving sheet to a back surface of an adjacent dye image-receiving sheet superimposed on the above-mentioned sheet and brought into contact with the above-mentioned dye image-receiving layer.
2. Description of the Related Art
Currently there is an enormous interest in the development of new types of thermal transfer dye printers capable of printing clear full color images or pictures.
In the operation of the thermal transfer dye printers, an image-receiving sheet having a dye image-receiving layer comprising a sublimating dye-dyeable resin is superimposed on an ink ribbon having a sublimating dye layer in such a manner that the image-receiving layer of the image-receiving sheet is brought into contact with the sublimating dye layer of the ink ribbon, and the ink ribbon is locally heated imagewise by a thermal head in accordance with electric signals corresponding to the image or pictures to be printed, to thereby thermally transfer the dye images or pictures having a color density corresponding to the amount of heat applied to the ink ribbon superimposed on the image-receiving sheet through the thermal head.
To form high quality dye images by a thermal transfer operation at a high speed in a thermal image printer, an image-receiving sheet is provided with an image-receiving layer comprising, as a main component, a resin material capable of being easily dyed with a sublimating dye. Also, a back coating layer is formed on a back surface opposite to the image-receiving layer surface of the image-receiving sheet to improve travelling properties, anti-static properties and slipping properties of the image-receiving sheet.
If the image-receiving sheet is fed into the printer incorrectly, the dye layer containing a dye and a binder resin of the ink ribbon is fuse-adhered to the back surface of the image-receiving sheet and thus movement of the image-receiving sheet through the printer is impeded. To prevent the above-mentioned impediment, in the conventional image-receiving sheet, an optically or magnetically readable detection mark is provided on the back surface of tile image-receiving sheet, and when the image-receiving sheet is fed to the printer, inside out, the detection mark is detected by a sensor equipped in the printer and the detected image-receiving sheet is discharged from the printer without being printed so as to prevent fuse adhesion of the ink ribbon to the image-receiving sheet.
However, when the image-receiving sheet is used in the form of a plurality of cut sheet pieces, and the detection marks are placed in the wrong positions on the cut sheet pieces, the marks are outside of the detecting range of the sensor and thus cannot be detected. Accordingly, the detection marks must be located at predetermined positions with a margin allowance of error of 1 to 2 mm.
To provide the cut sheets each having a detection mark precisely .located at a predetermined position by cutting a continuous sheet having a plurality of detection marks located at predetermined intervals, a special precise cutter must be employed.
Further, when the conventional image-receiving sheets are superimposed on each other after a printing operation, the printed image-receiving layer of an image-receiving sheet sometimes lightly fuse-adheres to the back surface of an adjacent image-receiving sheet in direct contact with the above-mentioned image-receiving sheet, and a portion of the dye received in the image-receiving layer is transferred onto the back surface of the adjacent sheet so that the color density of the images retained in the image-receiving layer is reduced.